A comparative first-principles study of tetragonal TiAl and Ti4Nb3Al9 intermetallic compounds

A comparative study on the phase stability and elastic properties of tetragonal TiAl and Ti4Nb3Al9 was performed by first-principles calculations based on density functional theory. The results showed that the stability of Ti4Nb3Al9 phase is lower than that of TiAl. The polycrystal Ti4Nb3Al9 has the better ductility and the lower hardness, sound velocities and Debye temperature than TiAl. Meanwhile, Ti4Nb3Al9 has more significant anisotropy of elasticity than TiAl. The above results can provide a valuable reference for designing the novel γ-TiAl-based alloys with γ1 -Ti4Nb3Al9 phase.